Proc. Electron Beam Melting and Refining State of the Art, Bakish Materials Corp. , In Press, 2000.

In the Directed Vapor Deposition (DVD) process metals or compounds will be evaporated at high rates by EB in a reactive or non-reactive way. The vapor is entrained and conveyed towards the substrate by a supersonic jet with deposition rates exceeding 100 nm/s. The jet concentrates the vapor in a localized stream with very small opening angle. To overcome the restriction of low material density and columnar structure, which is demanded for certain applications or certain layers in layer stacks, an effective plasma activation for DVD coating was requested. Resulting demands on the plasma source are accordingly:

• High plasma density to provide a high degree of ionization in the very dense vapor and jet gas atmosphere.
• Plasma source has to be viable in the pressure range between 1 and 100 Pa.
• Plasma has to be localized to match the spread of the vapor gas jet.
• The charge carrier loss caused by the jet stream must not disable the plasma function.

It has been found that all these demands can be fulfilled successfully by a hollow cathode arc plasma discharge containing a low voltage electron beam (LVEB). For coating of nonconductive layers on conductive layers, additional pulsed bias applied to the substrate is suited for periodic negative upcharging of the surface to be coated.